Colorimeter

ABSTRACT

A calorimeter for measuring a color of light includes a color sensing device, a suspension means and a counterweight. The suspension means suspends the color sensing device in an operative relationship relative to a color producing device, while the counterweight is secured to the suspension means and balances the color sensing device in the operative relationship relative to the color producing device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuing Application of and claims priority toU.S. patent application Ser. No. 10/898,652, filed Jul. 23, 2004, whichis herein incorporated by reference in its entirety. The Ser. No.10/898,652 application in turn is a continuing application of and claimspriority to Ser. No. 10/251,426, filed Sep. 20, 2002, which claimsbenefit of U.S. provisional patent application Ser. No. 60/323,861,filed Sep. 21, 2001, all of which are incorporated herein by referencein their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to color measuring devices. It findsparticular application in conjunction with devices for measuring colorsproduced by a liquid crystal display (“LCD”) monitor and will bedescribed with particular reference thereto. It will be appreciated,however, that the invention is also amenable to other like applications.

2. Description of the Related Art

In the field of color rendering systems, it is commonly necessary tocalibrate color rendering devices such as printers to make print colorsoutput by the color rendering devices conform to standards and tocompensate for drift and other changes. Thus, calibration is required tofine tune the color response of the color rendering device.

Colorimeters are known for measuring colors of a sample. One type ofconventional colorimeter has been developed for measuring colorsproduced by a monitor (display). Two (2) common types of displaysinclude, for example, cathode ray tube (“CRT”) monitors and liquidcrystal display (“LCD”) monitors. Reasons for measuring colors displayedon a monitor include identifying actual colors being displayed and,optionally, comparing the actual displayed colors against standardaccepted colors. One reason for making such a comparison is formodifying the displayed colors to more closely match the standardaccepted colors (e.g., calibrating the monitor). For various reasons,monitors must be calibrated on a regular basis.

Until now, colorimeters have been designed to be used with CRT monitors.Because LCD monitors have several distinct characteristics compared toCRT monitors, colorimeters designed for use with CRT monitors do notalways work well with LCD monitors. For example, LCD monitors noticeablychange color with viewing angle. Furthermore, because LCD monitorsinclude a soft viewing screen, colors displayed on the screen may changeas a function of pressure applied to the screen. In fact, colors areoften completely destroyed if too much pressure is applied to a softviewing screen. It is to be understood that additional differences,which are not mentioned, exist between CRT and LCD monitors.

For the reasons discussed above, calorimeters designed for CRT monitorsdo not always work well for measuring colors produced by LCD monitors.Therefore, calorimeters designed for CRT monitors are not practical forcalibrating LCD monitors.

The present invention provides a new and improved apparatus and methodwhich addresses the above-referenced problems.

SUMMARY OF THE INVENTION

In one embodiment, a colorimeter for measuring a color of light includesa color sensing device, a suspension means and a counterweight. Thesuspension means suspends the color sensing device in an operativerelationship relative to a color producing device, while thecounterweight is secured to the suspension means and balances the colorsensing device in the operative relationship relative to the colorproducing device.

In one aspect, the suspension means includes a flexible material securedto the color sensing device.

In another aspect, the flexible material includes rubber.

In another aspect, the suspension means further includes a dock. Theflexible material is secured to the color sensing device via the dock.The counterweight is secured to the suspension means so that thecounterweight balances the color sensing device, dock, and means forreducing color distortion.

In another aspect, a means substantially limits light received by thesensing device to be light emitted from the color producing devicewithin a predetermined angle.

In another aspect, the means for substantially limiting light is abaffle.

In another aspect, the means for reducing color distortion includes ahousing secured to the color sensing device. A flat surface on thehousing contacts the color producing device. The flat surfacesubstantially minimizes any pressure points on the color producingdevice.

In another embodiment, a method for measuring a color of light includessuspending a color sensing device in an operative relationship relativeto a color producing device, by securing the color sensing device to asuspension means, and balancing the color sensing device in theoperative relationship relative to the color producing device, using acounterweight secured to the suspension means.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which are incorporated in and constitute apart of the specification, embodiments of the invention are illustrated,which, together with a general description of the invention given above,and the detailed description given below, serve to exemplify theembodiments of this invention.

FIGS. 1A and 1B illustrate front and side views, respectively, of acolorimeter system according to one embodiment of the present invention;

FIG. 2 illustrates a perspective view of a baffle according to oneembodiment of the present invention;

FIGS. 3A illustrates an isometric top view of a baffle housing accordingto one embodiment of the present invention;

FIG. 3B illustrates a bottom view of the baffle housing according to oneembodiment of the present invention;

FIG. 3C illustrates a top view of a baffle housing according to oneembodiment of the present invention;

FIG. 4 illustrates a dock according to one embodiment of the presentinvention;

FIGS. 5A and 5B illustrate a hanger according to one embodiment of thepresent invention; and

FIG. 6 illustrates a counterweight according to one embodiment of thepresent invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B illustrate a calorimeter system 10 for measuring colorfrom a color producing device 12 according to the present invention. Inone embodiment, the color producing device 12 is a monitor having a softscreen display, which distorts colors upon the application of pressure(e.g., a liquid crystal display (“LCD”) monitor). However, it is to beunderstood that other types of monitors (e.g., cathode ray tube (“CRT”)monitors) are also contemplated in other embodiments.

The calorimeter system 10 includes a suspension device 14, a suspensionmeans 16, a dock 18, and a color sensing device (e.g., a colorimeter)20. The suspension device 14 is secured to the monitor 12 and,optionally, includes portions 14 a, 14 b that extend in differentdirections (e.g., substantially opposite directions) over and beyond theedges of the monitor 12.

With reference to FIGS. 1A, IB, and 2, a baffle 30 is designed tosubstantially limit light received by the sensing device 20 to be lightemitted from the monitor 12 within a predetermined angle (e.g., lightemitted from the monitor 12 within ±45°). For example, substantially theonly light received by the sensing device 20 is light that is emitted bythe monitor 12 at ±45° relative to the sensing device 20. In otherwords, the baffle 30 blocks light, which is not emitted by the monitor12 within the predetermined angle relative to the sensing device 20,from reaching the sensing device 20. In one embodiment, thepredetermined angle is ±45°. However, other predetermined angles arealso contemplated in other embodiments. In this manner, light includingdistorted color(s), due to large emission angles, is prevented fromentering the colorimeter 20.

In one embodiment, the baffle 30 includes ears 31 a, 31 b and one ormore passages 32. The passages 32 are shown in the embodimentillustrated in FIG. 2 as honeycomb-shaped; however, other shapes for thepassages 32 are contemplated in alternate embodiments. The passages 32direct light emitted from monitor 12 within the predetermined angle tothe sensing device 20. Light emitted from the monitor 12 outside thepredetermined angle is prevented from reaching the sensing device 20. Itis to be understood that the passages 32 are designed and constructed asa function of the predetermined angle. Therefore, the design andconstruction of the passages 32 in one embodiment, which passes lightemitted by the monitor 12 at ±45° relative to the sensing device 20, isdifferent than the design and construction of the passages 32 in anotherembodiment, which, for example, passes light emitted by the monitor 12at ±30° relative to the sensing device 20.

Optionally, a filter 34 is secured between the baffle 30 and the sensingdevice 20. The filter 34 blocks light of a predetermined frequencyemitted from the monitor 12. In one embodiment, the filter 34 is aninfrared (‘TR”) filter (e.g., a piece of I7R blocking glass). Such an IRfilter 34 is useful for LCD monitors that tend to emit light atwavelengths greater than about 850 nanometers (e.g., IR light), whichhas the potential to adversely affect colorimeters not specificallydesigned to block IR light. It is to be understood that although thefilter 34 is described in one embodiment as being an IR filter, otherembodiments including other types of filters are also contemplated.

With reference to FIGS. IB. 2, and 3A-3C, a baffle housing 50 covers thebaffle 30. The housing 50 is designed to serve multiple functions. Forexample, the housing 50 optionally includes a recess 52 in the center(see FIG. 3B) for securing the filter 34 in place. Furthermore, thehousing 50 optionally includes a pair of ribs 54 a, 54 b for securingthe honeycomb baffle 30 in place. In one embodiment, bosses (e.g., four(4)) 56 a, 56 b, 56 c, 56 d secure the baffle housing 50 to the sensingdevice 20 in a stable and repeatable manner. Partial walls 60 (see FIG.3A) emanate from the bosses 56. The walls 60 are designed such that thebaffle housing 50 is restricted to fit into the sensing device 20 inonly a single direction. Such a restriction guarantees that theorientation of the baffle housing 50 relative to the sensing device 20is constant. Similarly, slots 61 a, 61 b on the housing 50 are designedto mate with the ears 31 to guarantee that the orientation of thehousing 50 relative to the baffle 30 is constant.

Optionally, the baffle housing 50 also includes a large, flat surfacefor a foot 62 to be attached. The foot 62 is typically a soft (e.g.,foam) material. In one embodiment, the housing includes three (3) foamfeet 62. However, other embodiments, which include other numbers of foamfeet 62 are also contemplated. The foam feet 62 ensure the pressurepoints are dispersed on the monitor 12 and substantially minimized whenthe calorimeter 20 is taking measurements. Consequently, any colordistortion on the portion of the monitor 12 that projects light to thecolor sensing device 20 is minimized. In this sense, the feet 62 act asa means for reducing color distortion on the monitor 12.

With reference to FIG. 4, a dock 70 is designed to slip over and firmlyhold the color sensing device 20. A barb 72 is located at one end of thedock 70. The barb 72 is designed to secure a first end of the suspensionmeans 16. In one embodiment, the suspension means 16 includes a flexiblematerial (e.g., a string, ribbon, a flexible plastic, or stretchablematerial such as a rubber (e.g., a rubber tubing)). However, otherembodiments, in which the suspension means 16 includes a substantiallyrigid material (e.g., a rigid plastic) are also contemplated. Duringuse, the suspension means 16 is inserted through a hole 74 in thesuspension device 14 (see FIG. SA). A second end of the rubber tubing 16terminates at a counterweight 76 (see FIGS. IB and 6), which has a barb78 at an end. The barb 78 is designed to secure a second end of thesuspension means 16. The counterweight 76 is contemplated to have a massapproximately equal to that of the dock 18 and color sensing device 20.

In use, the suspension means 16 (e.g., tubing) is passed through thesuspension device 14. The ends of the suspension means 16 are affixed tothe dock 70 and the counterweight 76. The suspension device 14 is set onthe top, front edge of the monitor 12, which is to be measured with thecolor sensing device 20. The dock 70 is placed (suspended or hung) infront of the monitor 12 and the counterweight 76 is suspended (hung) tothe rear. The counterweight 76 balances the color sensing device 20,dock 70, and means for reducing color distortion.

The baffle housing 50, with the foam foot 62, baffle 30 and IR filter 34in place, is attached to the color sensing device 20 such that thebaffle 30 covers the entrance aperture of the color sensing device 20.The color sensing device 20 is then loaded into the dock 70 so that itgently rests against the monitor 12 with only the foam foot 62 incontact with the monitor 12. In this manner, the color sensing device 20is placed in a plane (e.g., substantially parallel to the monitor 12 toprovide selective horizontal and selective vertical placement of thecolor sensing device relative to the monitor 12) when the dock 70 isplaced in front of the monitor 12; similarly, the color sensing device20 is placed on a line (e.g., substantially perpendicular to the screenof monitor 12 to provide selective placement of the color sensing deviceaway from the screen of monitor 12) when the dock 70 is gently restedagainst the monitor 12. In this manner, the suspension device 14,suspension means 16, dock 18, and counterweight 76 act as a hangingmeans for placing the color sensing device 20 in an operativerelationship to the monitor 12.

The vertical position of the color sensing device 20 with respect to themonitor 12 is adjusted by sliding the hanging means 16 through thesuspension device 14. Once the proper vertical position is found, thehanging means 16 is pushed into a slot 82 on the back of the suspensiondevice 14 (see FIG. SB). In this manner, the hanging means 16 is lockedin place in the hanger 14.

Once the color sensing device 20 is correctly positioned relative to themonitor 12, measurements of colors produced by the monitor 12 may betaken. These measurements may be used, for example, to calibrate themonitor 12. Typically, in order to achieve the most accurate readings,the color sensing device 20 is positioned substantially in the center ofthe monitor 12. Therefore, the color sensing device 20 may be adjustedto a variety of monitor sizes via the hanging means 16.

While the present invention has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the invention, in its broaderaspects, is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general inventive concept.

1. A calorimeter for measuring a color of light, comprising: a color sensing device; a suspension means, for suspending the color sensing device in an operative relationship relative to a color producing device; and a counterweight secured to the suspension means, for balancing the color sensing device in the operative relationship relative to the color producing device.
 2. The calorimeter of claim 1, wherein the color sensing device is secured to the suspension means via a dock.
 3. The colorimeter of claim 1, wherein the suspension means comprises a flexible material.
 4. The calorimeter of claim 3, wherein the flexible material is at least one of: string, ribbon, flexible plastic or rubber.
 5. The calorimeter of claim 3, wherein the suspension means comprises a rigid material.
 6. The colorimeter of claim 1, wherein the suspension means comprises: a first end secured to the color sensing device; and a second end secured to the counterweight.
 7. The colorimeter of claim 1, wherein a mass of the counterweight is approximately equal to a mass of the color sensing device.
 8. The colorimeter of claim 1, further comprising: a suspension device for securing the suspension means to the color producing device.
 9. The colorimeter of claim 1, wherein the suspension means is adjustable to vary a vertical position of the color sensing device with respect to the color producing device.
 10. The calorimeter of claim 1, wherein the color sensing device further comprises: means for reducing color distortion on the color producing device when the color sensing device is positioned in the operative relationship relative to the color producing device.
 11. A method for measuring a color of light, comprising: suspending a color sensing device in an operative relationship relative to a color producing device, by securing the color sensing device to a suspension means; and balancing the color sensing device in the operative relationship relative to the color producing device, using a counterweight secured to the suspension means.
 12. The method of claim 11, wherein the suspending comprises: securing the color sensing device to the suspension means via a dock.
 13. The method of claim 11, wherein the suspension means comprises a flexible material.
 14. The method of claim 13, wherein the flexible material is at least one of: string, ribbon, flexible plastic or rubber.
 15. The method of claim 13, wherein the suspension means comprises a rigid material.
 16. The method of claim 11, wherein the suspension means comprises: a first end secured to the color sensing device; and a second end secured to the counterweight.
 17. The method of claim 11, wherein a mass of the counterweight is approximately equal to a mass of the color sensing device.
 18. The method of claim 11, further comprising: securing the suspension means to the color producing device.
 19. The method of claim 11, wherein the suspension means is adjustable to vary a vertical position of the color sensing device with respect to the color producing device.
 20. The method of claim 11, wherein the color sensing device further comprises: means for reducing color distortion on the color producing device when the color sensing device is positioned in the operative relationship relative to the color producing device. 